Methods and apparatus for producing syngas and alcohols

ABSTRACT

The present invention features methods and apparatus for the pyrolysis or torrefaction of a carbon-containing feedstock before it is converted to syngas. In some embodiments, biomass is first pretreated by torrefaction and/or pyrolysis, followed by devolatilization and/or steam reforming to produce syngas. Various mixtures of such pretreated biomass, combined with fresh biomass, can be employed to produce syngas. The syngas can be converted to alcohols, such as ethanol, or to other products.

PRIORITY DATA

This patent application claims priority under 35 U.S.C. §120 from U.S.Provisional Patent Application Nos. 61/014,408, 61/014,410, 61/014,412,and 61/014,415, each filed Dec. 17, 2007, and each of which is herebyincorporated herein by reference for all purposes.

FIELD OF THE INVENTION

This invention relates to flexible, efficient, and scalable methods andsystems to convert carbonaceous materials (such as biomass) intosynthesis gas and other downstream products (such as alcohols).

BACKGROUND OF THE INVENTION

Synthesis gas (hereinafter referred to as “syngas”) is a mixture of gascomprising predominantly hydrogen (H₂) and carbon monoxide (CO). Syngasis essentially a gaseous mixture of stable molecules that contain theelements carbon (C), hydrogen (H), and oxygen (O). Syngas is a platformintermediate in the chemical and biorefining industries and has a vastnumber of uses, as is well-known in the art. Syngas can be convertedinto alkanes, olefins, oxygenates, and alcohols. Some of these chemicalscan be blended into, or used directly as, diesel fuel, gasoline, andother liquid fuels. Syngas can also be directly combusted to produceheat and power.

Syngas can be produced, in principle, from virtually any materialcontaining C, H, and O. Such materials commonly include fossil resourcessuch as natural gas, petroleum, coal, and lignite; and renewableresources such as lignocellulosic biomass and various carbon-rich wastematerials. It is preferable to utilize a renewable resource to producesyngas because of the rising economic, environmental, and social costsassociated with fossil resources.

When biomass feedstocks are used, a significant portion of feedstockcosts can be attributed to the handling associated with moving thefeedstocks from their point of production to their point of furtherconversion or use. Handling solid forms of biomass is expensive for anumber of reasons, including the number of operations required and thelow bulk density of the feedstocks, which causes high transportationcosts.

Furthermore, it has been estimated that over 1 billion tons of drybiomass are available in the United States for conversion to renewablefuels. Much of this biomass, however, is located in remote locations.Economical transportation of biomass is usually limited to a distance ofup to about 75 miles because of transportation costs. Thus, there is asignificant amount of feedstock in locations that extend beyond therange of economical transportation using standard methods.

In view of the aforementioned limitations of the art, improved methodsand apparatus are needed to convert carbon-containing feedstocks such asbiomass into syngas, which can then be converted to alcohols or otherproducts. Preferably, improved methods would alleviate some of theeconomic burden associated with transportation.

SUMMARY OF THE INVENTION

In a first aspect relating to methods, the present invention provides amethod of forming syngas, the method comprising the steps of: (a)pyrolyzing or torrefying a carbon-containing first feed material to forma pyrolyzed or torrefied first feed material; and (b) converting thepyrolyzed or torrefied first feed material into syngas. Step (a) can beconducted in the presence of a catalyst.

The method can further include converting into syngas a second feedmaterial that has not been pyrolyzed or torrefied. The method canfurther include combining the pyrolyzed or torrefied first feed materialwith a second feed material that has not been pyrolyzed or torrefiedsuch that both the pyrolyzed or torrefied first feed material and thesecond feed material are converted into syngas.

In some embodiments, the method includes pyrolyzing a carbon-containingfirst feed material to form a pyrolyzed first feed material, torrefyinga carbon-containing feed second material to form a torrefied second feedmaterial, and converting the pyrolyzed first feed material and thetorrefied second feed material into syngas. In some embodiments, themethod includes introducing the torrefied first feed material into apyrolysis reactor to form a pyrolyzed first feed material. The methodcan be conducted, at least in part, in the presence of a catalyst.

The pyrolyzed or torrefied first feed material can be converted intosyngas by passing the pyrolyzed or torrefied first feed material througha heated reaction vessel, such as a steam reformer or partial-oxidationreactor, to form syngas. In some embodiments, conversion to syngascomprises the substeps of: (i) devolatilizing the pyrolyzed or torrefiedfirst feed material to form a gas phase and/or solid phase in adevolatilization unit; and (ii) passing the gas phase and/or solid phasethrough a heated reaction vessel to form syngas.

Certain embodiments provide for converting into syngas a pyrolyzed ortorrefied first feed material and a second carbon-containing feedmaterial that has not been pyrolyzed or torrefied. Certain embodimentsinclude pyrolyzing a carbon-containing first feed material to form thepyrolyzed first feed material, torrefying a carbon-containing third feedmaterial to form a torrefied third feed material, and converting thepyrolyzed first feed material, the second feed material, and thetorrefied third feed material into syngas. Other embodiments combine,prior to converting the material into syngas, the pyrolyzed or torrefiedfirst feed material and the second feed material.

In some embodiments, methods include converting the pyrolyzed ortorrefied first feed material and the second feed material into syngas.This particular method comprises the steps of: (i) devolatilizing thepyrolyzed or torrefied first feed material and the second feed materialto form a gas phase and/or solid phase in a devolatilization unit; and(ii) passing the gas phase and/or solid phase through a heated reactionvessel to form syngas. The torrefied first feed material can beintroduced into a pyrolysis reactor to form a pyrolyzed first feedmaterial.

Some embodiments provide a method of forming syngas, the methodcomprising the steps of: (a) devolatilizing a pyrolyzed or torrefiedfirst feed material to form a gas phase and solid phase in adevolatilization unit; and (b) passing the gas phase and solid phasethrough a heated reaction vessel to form syngas.

Pyrolysis of a carbon-containing feed material, optionally in thepresence of a catalyst, can form the first feed material. Or,torrefaction of a carbon-containing feed material, optionally in thepresence of a catalyst, can form the first feed material. A second feedmaterial that has not been pyrolyzed or torrefied can be mixed with thefirst feed material and converted into syngas. In some embodiments, boththe pyrolyzed or torrefied first feed material and the second feedmaterial are converted into syngas.

Certain embodiments include pyrolyzing a carbon-containing first feedmaterial to form the pyrolyzed first feed material, torrefying acarbon-containing third feed material to form a torrefied third feedmaterial, and converting the pyrolyzed first feed material, the secondfeed material, and the torrefied third feed material into syngas. Thepyrolyzed or torrefied first feed material and the second feed materialcan be combined prior to converting the pyrolyzed or torrefied firstfeed material and the second feed material into syngas. The torrefiedfirst feed material can be used to form a pyrolyzed first feed material.

Some embodiments employ modular units for at least some steps of themethods previously described.

Some embodiments further include the step of converting the syngas to aproduct, such as a product selected from the group consisting of analcohol, an olefin, an aldehyde, a hydrocarbon, an ether, hydrogen,ammonia, and/or acetic acid. The hydrocarbon can be a linear or branchedC₅-C₁₅ hydrocarbon. The alcohol can be methanol and/or ethanol.

A second aspect relates to apparatus for practicing some embodiments ofthe invention. In some of these embodiments, an apparatus is providedfor producing syngas comprising a pyrolysis and/or torrefaction reactorin communication with a devolatilization unit that is in communicationwith a heated reaction vessel. In some embodiments, the pyrolysisreactor, torrefaction reactor, or both of these reactors, is suitablefor containing one or more catalysts for pyrolysis or torrefaction.

In some embodiments, the apparatus further includes a device forcombining pyrolyzed feed material with feed material that has not beenpyrolyzed. In some embodiments, the apparatus further includes a devicefor combining torrefied feed material with feed material that has notbeen torrefied.

Some embodiments of this aspect provide an apparatus for producingsyngas comprising a pyrolysis and/or torrefaction reactor (which can becatalytic) in communication with a device for combining a pyrolyzed ortorrefied first feed material with a second feed material that has notbeen pyrolyzed or torrefied, wherein the device is in communication witha syngas reactor for converting the first feed material and the secondfeed material into syngas.

Certain apparatus include a device for combining pyrolyzed feed materialwith torrefied feed material, wherein the device is in communicationwith: (i) the pyrolysis reactor and/or the torrefaction reactor, and(ii) the syngas reactor. The syngas reactor can comprise adevolatilization unit that is in communication with a heated reactionvessel.

Some apparatus of the invention further include a product reactor forconverting syngas into a product, such as C₁-C₄ alcohols (e.g., methanoland/or ethanol), wherein the product reactor is in communication withthe syngas reactor.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

This detailed description illustrates by way of example, not by way oflimitation, the principles of the invention. This description willenable one skilled in the art to make and use the invention, anddescribes several embodiments, adaptations, variations, alternatives,and uses of the invention, including what is presently believed to bethe best mode of carrying out the invention. It should also be notedthat, as used in this specification and the appended claims, thesingular forms “a,” “an,” and “the” include plural referents unless thecontext clearly indicates otherwise. Unless defined otherwise, alltechnical and scientific terms used herein have the same meaning as iscommonly understood by one of ordinary skill in the art to which thisinvention belongs. If a definition set forth in this section is contraryto or otherwise inconsistent with a definition set forth in patents,published patent applications, and other publications that are hereinincorporated by reference, the definition set forth in this sectionprevails over the definition that is incorporated herein by reference.

Unless otherwise indicated, all numbers expressing reaction conditions,stoichiometries, and so forth used in the specification and claims areto be understood as being modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending at least upon the specificmeasurement technique.

The present invention features methods and apparatus for the pyrolysisor torrefaction of a feedstock before it is converted to syngas.Pyrolysis and torrefaction produce a relatively energy-dense feedstock(e.g., by the removal of water and/or the densification of thefeedstock), thereby reducing the transportation costs of the resultingfeedstocks.

In some embodiments, a pyrolyzed feedstock and a torrefied feedstock areconverted to syngas. In other embodiments, a pyrolyzed feedstock and afeedstock that has not undergone pyrolysis or torrefaction are convertedto syngas. Some embodiments convert a torrefied feedstock and afeedstock that has not undergone pyrolysis or torrefaction to syngas. Insome embodiments, a torrefied feedstock, a pyrolyzed feed stock, and afeedstock that has not undergone pyrolysis or torrefaction are convertedto syngas. In some embodiments, a fossil fuel (e.g., crude oil, coal,and/or petroleum) and one or more of the following are converted tosyngas: a pyrolyzed feedstock, a torrefied feedstock, and a feedstockthat has not undergone pyrolysis or torrefaction.

In one aspect, the invention features methods and systems that usemodular units for the pyrolysis or torrefaction of a feedstock. Forexample, a feedstock can be reacted in a modular pyrolysis ortorrefaction reactor and then transported to a plant for furtherprocessing, such as the conversion of the reacted feedstock to syngas orother downstream products. In some embodiments, modular units are alsoused to devolatilize and/or stream reform the pyrolyzed or torrefiedfeedstock. For example, a pyrolyzed or torrefied feedstock can beintroduced into a modular unit for devolatilizing the feedstock. In someembodiments, the modular devolatilization unit is in communication with(such as operably linked to) a modular unit for steam reforming theproduct of the devolatilization unit, thereby forming syngas. In someembodiments, the product from the modular devolatilization unit istransported to a plant for further processing, such as the conversion tosyngas or other downstream products.

“Biomass,” for the purposes of the present invention, is any materialnot derived from fossil resources and comprising at least carbon,hydrogen, and oxygen. Biomass includes, for example, plant andplant-derived material, vegetation, agricultural waste, forestry waste,wood waste, paper waste, animal-derived waste, poultry-derived waste,and municipal solid waste. Other exemplary feedstocks include cellulose,hydrocarbons, carbohydrates or derivates thereof, charcoal, andrenewable feedstocks. The present invention can also be used forcarbon-containing feedstocks other than biomass, such as a fossil fuel(e.g., coal or petroleum). Thus, any method, apparatus, or systemdescribed herein in reference to biomass can alternatively be used withany other feedstock.

The methods and systems of the invention can accommodate a wide range offeedstocks of various types, sizes, and moisture contents. In someembodiments of the invention, the biomass feedstock can include one ormore materials selected from: timber harvesting residues, softwoodchips, hardwood chips, tree branches, tree stumps, leaves, bark,sawdust, off-spec paper pulp, corn, corn stover, wheat straw, ricestraw, sugarcane bagasse, switchgrass, miscanthus, animal manure,municipal garbage, municipal sewage, commercial waste, grape pumice,almond shells, pecan shells, coconut shells, coffee grounds, grasspellets, hay pellets, wood pellets, cardboard, paper, plastic, andcloth. A person of ordinary skill in the art will readily appreciatethat the feedstock options are virtually unlimited.

According to the present invention, selection of a particular feedstockor feedstocks is not regarded as technically critical, but is carriedout in a manner that tends to favor an economical process. Typically,regardless of the feedstocks chosen, there can be (in some embodiments)screening to remove undesirable materials. The feedstock can optionallybe dried prior to processing. There can also, but need not, be reductionof particle size prior to conversion of the feedstock to syngas.Particle size is not, however, regarded as critical to the invention.

For the purposes of the present invention, “reforming” or “steamreforming” refers to the production of syngas when steam is thereactant. “Partial oxidation” refers to the production of syngas whenoxygen is the reactant. “Gasification” generally refers to theproduction of a mixture of at least CO, CO₂, and H₂, and can include oneor more of devolatilization, reforming, or partial oxidation, as well assome amount of pyrolysis, combustion, water-gas shift, and otherchemical reactions.

Some exemplary variations provide a process for synthesizing syngas frombiomass or other carbon-containing material. Part or all of thefeedstock is introduced into a feedstock reactor, such as a pyrolysisreactor or torrefaction reactor. The product from the feedstock reactoris then introduced into a syngas reactor. In some embodiments, a portionof the feedstock is not introduced into the feedstock reactor. Instead,this portion is added directly to a syngas reactor.

In some embodiments, the syngas reactor includes a devolatilization unitand/or reformer reactor. The syngas produced in the syngas reactor canbe cooled and compressed. In some variations, the syngas is filtered,purified, or otherwise conditioned prior to being converted to anotherproduct. For example, syngas may be introduced to a syngas conditioningsection, where benzene, toluene, ethyl benzene, xylene, sulfurcompounds, nitrogen, metals, and/or other impurities or potentialcatalyst poisons are optionally removed from the syngas. In someembodiments, the syngas is introduced into one or more product reactorsfor the conversion of syngas into another product, such as methanoland/or ethanol.

Exemplary feedstock reactors include one or more standard pyrolysisreactors and/or torrefaction reactors. In some embodiments, a pyrolysisreactor is used to pyrolyze a portion of or the entire feedstock usingstandard methods (see, for example, Czernik and Bridgwater, Energy &Fuels, 18:590-598, 2004, and Mohan et al., Energy & Fuels, 20:848-889,2006, which are each hereby incorporated by reference in theirentireties, particularly with respect to pyrolysis reactors andmethods).

Pyrolysis is the thermal decomposition of a feed stock. Preferably, lessoxygen is present than required for complete combustion of the feedstock(such as about or less than 40, 30, 20, 10, 5, 1, 0.5, or 0.01% of theoxygen that is required for complete combustion of the feedstock). Insome embodiments, pyrolysis is performed in the absence of oxygen.

Exemplary changes that may occur during pyrolysis include any of thefollowing: (i) heat transfer from a heat source increases thetemperature inside the feedstock; (ii) the initiation of primarypyrolysis reactions at this higher temperature releases volatiles andforms a char; (iii) the flow of hot volatiles toward cooler solidsresults in heat transfer between hot volatiles and cooler unpyrolyzedfeedstock; (iv) condensation of some of the volatiles in the coolerparts of the feedstock, followed by secondary reactions, can producetar; (v) autocatalytic secondary pyrolysis reactions proceed whileprimary pyrolytic reactions simultaneously occur in competition; and(vi) further thermal decomposition, reforming, water-gas shiftreactions, free-radical recombination, and/or dehydrations can alsooccur, which are a function of the residence time, temperature, andpressure profile.

Pyrolysis partially dehydrates the feedstock. In various embodiments,pyrolysis removes greater than or about 5, 10, 20, 30, 40, 50, 60, 70,80, 90% or more of the water from the feedstock. It can be beneficial,but not necessary, to remove at least 90% of the water initiallypresent. The products from the pyrolysis reactor are typically a gas, anoil (also referred to as “pyrolysis oil” or “bio-oil”), and a char.

Any standard pyrolysis reactor can be used to pyrolyze the feedstock.Exemplary reactor configurations include, but are not limited to,augers, ablative reactors, rotating cones, fluidized-bed reactors (e.g.,circulating fluidized-bed reactors), entrained-flow reactors, vacuummoving-bed reactors, transported-bed reactors, fixed-bed reactors, andmicrowave-assisted pyrolysis reactors.

In some embodiments in which an auger is used, the feedstock and sandare fed at one end of a screw. The screw mixes the sand and feedstockand conveys them through the reactor. The screw can provide good controlof the feedstock residence time and does not dilute the pyrolyzedproducts with a carrier or fluidizing gas. The sand is reheated in aseparate vessel.

In some embodiments in which an ablative process is used, the feedstockis moved at a high speed against a hot metal surface. Ablation of anychar forming at the particle surface maintains a high rate of heattransfer. Preferably, the apparatus utilizes a metal surface spinning ata high speed within a bed of feedstock, which prevents any dilution ofthe products. As an alternative, the feedstock particles may besuspended in a carrier gas and introduced at a high speed through acyclone whose wall is heated. The products are diluted with the carriergas.

In some embodiments, preheated hot sand and feedstock are introducedinto a rotating cone. Due to the rotation of the cone, the mixture ofsand and feedstock is transported across the cone surface by centrifugalforce. Like other shallow transported-bed reactors, relatively fineparticles are used to obtain a good liquid yield.

In some embodiments in which a fluidized-bed reactor is used, thefeedstock is introduced into a bed of hot sand fluidized by a gas, whichis usually a recirculated product gas. High heat transfer rates fromfluidized sand result in rapid heating of the feedstock. There can besome ablation by attrition with the sand particles. Heat is usuallyprovided by heat-exchanger tubes through which hot combustion gas flows.There is some dilution of the products, which makes it more difficult tocondense and then remove the bio-oil mist from the gas exiting thecondensers.

In some embodiments in which a circulating fluidized-bed reactor isused, the feedstock is introduced into a circulating fluidized-bed ofhot sand. Gas, sand, and feedstock move together. Exemplary transportgases include recirculated product gases and combustion gases. Highheat-transfer rates from the sand ensure rapid heating of the feedstock,and ablation is stronger than with regular fluidized beds. A fastseparator separates the product gases and vapors from the sand and charparticles. The sand particles are reheated in a fluidized burner vesseland recycled to the reactor.

Any standard reaction conditions can be used to pyrolyze the feedstockin the pyrolysis reactor (see, for example, Czernik and Bridgwater,Energy & Fuels, 18:590-598, 2004; and Mohan et al, Energy & Fuels,20:848-889, 2006). One skilled in the art can select a combination oftemperature, pressure, and residence time that produces a liquid as aproduct of the pyrolysis process (rather than only forming a solidand/or gas). For example, if the reaction temperature, pressure, and/orresidence time is too low or too high, the product may be primarily asolid. A skilled artisan, by routine experimentation, can adjust theparameters to obtain primarily a liquid as the pyrolyzed product.

In some embodiments, fast pyrolysis is used. Fast pyrolysis is ahigh-temperature process in which feedstock is rapidly heated. In someembodiments, the feedstock is heated in the absence of oxygen. Thefeedstock decomposes to generate vapors, aerosols, and somecharcoal-like char. After cooling and condensation of the vapors andaerosols, a dark brown mobile liquid is formed that has a heating valuethat is about half that of conventional fuel oil. Rapid heating andrapid quenching can produce the intermediate pyrolysis liquid products,which condense before further reactions break downhigher-molecular-weight species into gaseous products. Fast pyrolysisprocesses typically produce 60-75 wt % of liquid bio-oil, 15-25 wt % ofsolid char, and 10-20 wt % of noncondensable gases, for example,depending on the feedstock used.

Pyrolysis can be performed in the presence of a catalyst. Exemplarycatalysts include heterogeneous catalysts (such as SiO₂—Al₂O₃,Pt/SiO₂—Al₂O₃, WO_(x)/ZrO₂, SO_(x)/ZrO₂), zeolites (such as HY-zeolite,α-zeolite, HZSM-5, ZSM-5, or klinoptilolite), acid catalysts, claycatalysts (e.g., acidified or activated clay catalysts), Al-MCM-41 typemesoporous catalysts, activated alumina, Co—Mo catalysts (such asCriterion-534), and Ni/Al co-precipitated catalysts. In someembodiments, a cation such as K⁺, Li⁺, or Ca²⁺ can be used to increasethe selectivity and yield of char and/or to lower the selectivity andyield of tar during pyrolysis.

In some embodiments, the feedstock is finely ground before it is addedto the pyrolysis reactor to facilitate high heating rates and fast heattransfer. In some embodiments, the reaction temperature is between about300-600° C., such as about 450° C., when a pyrolysis catalyst is used.In particular embodiments, the temperature is between about 300-400° C.,about 400-500° C., or about 500-600° C. In some embodiments, use of apyrolysis catalyst allows a lower temperature to be used, such as about250-450° C. High reaction rates minimize char formation. Under someconditions, no char is formed.

In some embodiments, the pressure is between about 0 to about 2,000 psi,such as between about 0 to about 50 psi. In some embodiments, theresidence time is between about 0.1 seconds to about 10 seconds, such asabout 1-5 seconds. In some embodiments, the pyrolysis vapors andaerosols are rapidly cooled to generate pyrolysis oil.

Slow pyrolysis can also used. In slow pyrolysis, the feedstock is heatedto about 500° C. The vapor residence time varies from about 5 minutes toabout 30 minutes. Vapors do not escape as rapidly in slow pyrolysis asthey do in fast pyrolysis. Thus, components in the vapor phase continueto react with each other as the solid char and any liquid are beingformed. The heating rate in slow pyrolysis is typically much slower thanthat used in fast pyrolysis. A feedstock can be held at constanttemperature or slowly heated. Vapors can be continuously removed as theyare formed.

In some embodiments, vacuum pyrolysis is used. In this method, thefeedstock is heated in a vacuum to decrease the boiling point and/oravoid adverse chemical reactions. Slow or fast heating rates can beused. Some embodiments employ a temperature of about 450° C. and apressure of between about 1-5 psi.

The pyrolysis oil may contain water, such as about 10 to about 25% water(weight %). If desired, part or the entire water layer of the pyrolysisoil can be removed before it is added to a devolatilization unit and/orreformer reactor using standard methods, such as phase separation orseparation based on differences in volatility. Exemplary methods includephase separation by decanting, distillation, and separation usingmembranes. In some embodiments, none of the water is removed from thepyrolysis oil before it is added to the devolatilization unit and/orreformer reactor. The water in the pyrolysis oil can provide a source ofsteam, which can be used to increase the hydrogen content of the syngasthrough the water-gas shift reaction, if desired.

In some embodiments, the gas and/or solid products from the pyrolysisreactor are recycled through the pyrolysis reactor or are burned togenerate energy.

Some variations of the present invention utilize the principles oftorrefaction. Torrefaction can improve the properties of acarbon-containing feedstock (e.g., biomass). Torrefaction consists of aslow heating of feedstock in an inert atmosphere to a maximumtemperature of about 300° C. The treatment yields a solid uniformproduct with a lower moisture content and a higher energy contentcompared to the initial feedstock. The process may be called mildpyrolysis, with removal of smoke-producing compounds and formation of asolid product, retaining (in some embodiments) about 70% of the initialweight and about 90% of the original energy content.

Torrefied material typically has the following properties: (i)hydrophobic nature (e.g., the material does not regain humidity instorage and therefore, unlike wood and charcoal, is stable with awell-defined composition); (ii) lower moisture content and highercalorific values compared to the initial feedstock; (iii) formation ofless smoke when burned; and (iv) higher density and similar mechanicalstrength compared to the initial feedstock.

In some embodiments, a torrefaction reactor is used to torrefy a portionof or the entire feedstock using standard methods, such as thosedescribed in WO 2007/078199 or in Bergman and Kiel, “Torrefaction forbiomass upgrading,” 14^(th) European Biomass Conference & Exhibition,ENC-RX-05-180, Paris, France, 2005, which publications are each herebyincorporated by reference in their entireties, particularly with respectto torrefaction reactors and methods.

Any standard torrefaction reactor can be used to torrefy the feedstock.Exemplary reactor configurations include, but are not limited to,augers, ablative reactors, rotating cones, fluidized-bed reactors (e.g.,circulating fluidized-bed reactors), entrained-flow reactors, vacuummoving-bed reactors, transported-bed reactors, and fixed-bed reactors.In some embodiments, a feedstock is torrefied before it is added to adevolatilization unit or reformer reactor. In other embodiments, afeedstock is torrefied while it is contained in a devolatilization unit.

Any standard reaction conditions can be used to torrefy the feedstock inthe torrefaction reactor. One skilled in the art can readily select acombination of temperature, pressure, and residence time that produces adried solid as a product of the torrefaction process. In someembodiments, the reaction temperature is between about 150-300° C., suchas about 200-300° C. A variety of pressures can be used fortorrefaction, such as atmospheric pressure or greater. In someembodiments, the residence time is between about 10 minutes to about 8hours. The residence time is preferably adjusted based on the type offeedstock used. In some embodiments, torrefaction is performed in theabsence of oxygen. In some embodiments, the torrefied feedstock iscrushed or densified (e.g., compressed to form pellets using apelletizer) using standard methods to form smaller particles that areeasier to transport and/or easier to mix with other feedstocks.

In some embodiments, torrefaction is performed in the presence of acatalyst. Exemplary catalysts for torrefaction include heterogeneouscatalysts (such as SiO₂—Al₂O₃, Pt/SiO₂—Al₂O₃, WO_(x)/ZrO₂, SO_(x)/ZrO₂),zeolites (such as HY-zeolite, α-zeolite, HZSM-5, ZSM-5, orklinoptilolite), acid catalysts, clay catalysts (e.g., acidified oractivated clay catalysts), Al-MCM-41 type mesoporous catalysts,activated alumina, Co-Mo catalysts (such as Criterion-534), and Ni/Alco-precipitated catalysts.

A torrefied feedstock (such as a solid product from a torrefactionreactor) can be added to a pyrolysis reactor (such as a pyrolysisreactor described herein) to further process the torrefied feedstockbefore adding it to a syngas reactor, devolatilization unit, and/orreformer reactor.

In some embodiments, a pyrolyzed product (such as the pyrolysis oiland/or solid product from a pyrolysis reactor) is combined with atorrefied product (such as a solid product from a torrefaction reactor)before they are added to a devolatilization unit and/or reformerreactor. Any standard method can be used for this mixing. In someembodiments, a screw is used to mix the pyrolyzed products and torrefiedproducts. In some embodiments, a feed mixer is used, such as a verticalor horizontal mixer. A vertical mixer consists, for example, of avertical screw which takes material to the top where it falls back downagain, and repeats that process to mix materials. A horizontal mixerincludes, for example, paddles or blades attached to a horizontal rotor.

In some embodiments, a mixer with two counter-rotating rotors in a largehousing is used to mix the pyrolyzed products and torrefied products. Insome embodiments, a Banbury mixer is used. A Banbury mixer includes, forexample, two contra-rotating spiral-shaped blades encased in segments ofcylindrical housings, intersecting so as to leave a ridge between theblades. The blades may be cored for circulation of heating or coolingmedia.

In some embodiments, pyrolysis oil is sprayed onto the torrefiedproduct, using, for example, a standard spray pump and nozzle todistribute the pyrolysis oil as a mist over the torrefied product. Ifdesired, the pyrolyzed products and torrefied products can be furthermixed after the pyrolysis oil is sprayed onto the torrefied product.

In some embodiments, a pyrolyzed product (such as the pyrolysis oiland/or solid product from a pyrolysis reactor) and/or a torrefiedproduct (such as a solid product from a torrefaction reactor) iscombined with another feedstock (such as a feedstock that has notundergone pyrolysis or torrefaction) before they are added to adevolatilization unit. Any standard method can be used for this mixing,such as any of the methods described above for mixing pyrolyzed productsand torrefied products.

When different feedstocks are used, they can be used in any ratio andthey can be introduced in the same or different locations of adevolatilization unit or reformer reactor. Any ratio of pyrolyzedproducts to torrefied products can be used, such as a ratio of about1:0.01 to about 1:100 by weight, such as about 1:0.1, 1:1, or 1:10. Anyratio of pyrolyzed products to another feedstock (such as a feedstockthat has not undergone pyrolysis or torrefaction) can be used, such as aratio of about 1:0.01 to about 1:00 by weight, such as about 1:0. 1,1:1, or 1:10. Any ratio of torrefied products to another feedstock (suchas a feedstock that has not undergone pyrolysis or torrefaction, e.g.,biomass or a fossil fuel) can be used, such as a ratio of about 1:0.01to about 1:100 by weight. It will be understood that the specificselection of feedstock ratios can be influenced by many factors,including economics (feedstock prices and availability), processoptimization (depending on feedstock composition profiles), utilityoptimization, equipment optimization, and so on.

Any standard syngas reactor can be used convert a feedstock or a mixtureof feedstocks (such as a mixture of two or more of the following: apyrolyzed feedstock, a torrefied feedstock, and a feedstock that has notbeen pyrolyzed or torrefied) into syngas. Exemplary reactorconfigurations include, but are not limited to, fixed-bed reactors (suchas countercurrent or co-current fixed-bed reactors), stationaryfluidized-bed reactors, circulating fluid-bed reactors (such as thosedeveloped by Varnamo, Sweden), oxygen-driven fluid-bed reactors (such asthose developed by Biosyn, Canada), bubbling fluid-bed reactors,pressurized fluid-bed reactors (such as pressurized bubbling orcirculating fluid-bed reactors), moving-bed gasifiers (such as thosedeveloped by BMG, Finland), countercurrent moving-bed reactors,co-current moving-bed reactors, cross-current moving-bed reactors,entrained flow reactors (such as slagging or slag bath entrained-flowreactors), oxygen-blown gasifiers, steam gasifiers, and multistagegasifiers (such as those with a unit for combustion and a unit forgasification or those with a devolatilization unit and a reformerreactor). In some embodiments, the syngas reactor includes adevolatilization unit and a reformer reactor (see, for example, U.S.Pat. No. 6,863,878 and U.S. Patent. App. Pub. No. 2007/0205092, whichare each incorporated herein by reference in their entireties).

In some embodiments in which a counter-current fixed-bed reactor isused, the reactor consists of a fixed bed of a feedstock through which a“gasification agent” (such as steam, oxygen, and/or air) flows incounter-current configuration. The ash is either removed dry or as aslag.

In some embodiments in which a co-current fixed-bed reactor is used, thereactor is similar to the counter-current type, but the gasificationagent gas flows in co-current configuration with the feedstock. Heat isadded to the upper part of the bed, either by combusting small amountsof the feedstock or from external heat sources. The produced gas leavesthe reactor at a high temperature, and much of this heat is transferredto the gasification agent added in the top of the bed, resulting in goodenergy efficiency. Since tars pass through a hot bed of char in thisconfiguration, tar levels are much lower than the counter-current type.

In some embodiments in which a fluidized-bed reactor is used, thefeedstock is fluidized in oxygen and steam or air. The ash is removeddry or as heavy agglomerates that defluidize. The temperatures arerelatively low in dry-ash reactors, so the feedstock is desirably highlyreactive. The agglomerating reactors have slightly higher temperatures.Feedstock throughput is higher than for the fixed bed, but not as highas for the entrained flow reactor. Recycle or subsequent combustion ofsolids can be used to increase conversion. Fluidized-bed reactors aremost useful for feedstocks that form highly corrosive ash that woulddamage the walls of slagging reactors.

In some embodiments in which an entrained-flow reactor is used, a drypulverized solid, an atomized liquid feedstock, or a feedstock slurry isgasified with oxygen or air in co-current flow. The gasificationreactions take place in a dense cloud of very fine particles. The hightemperatures and pressures also mean that a higher throughput can beachieved; thermal efficiency is somewhat lower, however, as the gas iscooled before it can be cleaned with existing technology. The hightemperatures also mean that tar and methane are not present in theproduct gas; the oxygen requirement can be higher than for the othertypes of reactors.

Entrained-flow reactors remove the major part of the ash as a slag, asthe operating temperature is well above the ash fusion temperature. Asmaller fraction of the ash is produced either as a very fine dry flyash or as a black-colored fly-ash slurry. Some feedstocks, in particularcertain types of biomass, can form slag that is corrosive for ceramicinner walls that serve to protect the reactor outer wall. However, someentrained-bed reactors do not possess a ceramic inner wall but have aninner water- or steam-cooled wall covered with partially solidifiedslag. These types of reactors do not suffer from corrosive slags. Somefeedstocks have ashes with very high ash-fusion temperatures. In thiscase, limestone can be mixed with the feedstock prior to gasification.Addition of limestone usually can lower the fusion temperatures. In someembodiments, the feedstock is pulverized, which requires somewhat moreenergy than for the other types of reactors.

Torrefied or pyrolyzed biomass (or other C-containing feedstock) can betransported by any known means, such as by truck, train, ship, barge,tractor trailer, or any other vehicle or means of conveyance (e.g., apipeline). In some embodiments, a heated truck is used to transportpyrolysis oil or torrefied material to a unit for conversion toproducts.

The present invention, in certain variations, can utilize modular unitsfor the pyrolysis, torrefaction, devolatilization, reforming, and/orgasification of biomass and other feedstocks to form useful products. A“modular unit” means an apparatus that is capable of either operablystanding alone or of being operably connected with at least one othermodular unit.

In some embodiments, a modular unit for the pyrolysis or torrefaction isin communication with (such as operably linked to) a modular unit forconverting the pyrolyzed or torrefied feedstock into syngas. In someembodiments, a modular unit for the pyrolysis or torrefaction is incommunication with (such as operably linked to) a modular unit fordevolatizing the feedstock. In some embodiments, these modular units arealso in communication with a modular unit for reforming the product ofthe devolatilization unit and/or one or more modular units for theconversion of syngas to another product, such as an alcohol.

Placement of modular units near feedstock sources can minimizetransportation energy and thereby increase the yield of syngas (and/orderivatives of syngas) per amount of energy expended.

In some embodiments, the modular unit is a portable unit, such as a unitmounted on skids, a platform, or a conveyer to facilitate the movementof the modular unit between different locations. In some embodiments,the modular unit can be assembled and/or disassembled in fewer steps orin less time than for a unit that is not capable of being transported.

In some embodiments, a modular unit can be easily dismantled into one ormore pieces that can be transported on the back of a tractor trailer. Insome embodiments, the modular unit weights less than or about 80,000,60,000, or 40,000 lbs. In some embodiments, the modular unit can betransported in a vehicle that satisfies the specifications for vehiclesize and weight established by the U.S. Department of Transportation,which governs the use of the interstate highway system.

Certain embodiments use modular units and/or methods of distribution ofthese units in accordance with the description in co-pending U.S. patentapplication Ser. No. 12/166,117, entitled “MODULAR AND DISTRIBUTEDMETHODS AND SYSTEMS TO CONVERT BIOMASS TO SYNGAS,” with an effectivepriority date of Jul. 9, 2007, whose assignee is the same as theassignee of this patent application, and which is hereby incorporatedherein by reference.

The syngas produced as described according to the present invention canbe utilized in a number of ways. Syngas can generally be chemicallyconverted and/or purified into hydrogen, carbon monoxide, methane,graphite, olefins (such as ethylene), oxygenates (such as dimethylether), alcohols (such as methanol and ethanol), paraffins, and otherhydrocarbons.

The syngas produced according to the methods and systems of theinvention can further produce: a linear or branched C₅-C₁₅ hydrocarbon,diesel fuel, gasoline, waxes, or olefins by Fischer-Tropsch chemistry;methanol, ethanol, and mixed alcohols by a variety of catalysts;isobutane by isosynthesis; ammonia by hydrogen production followed bythe Haber process; aldehydes and alcohols by oxosynthesis; and manyderivatives of methanol including dimethyl ether, acetic acid, ethylene,propylene, and formaldehyde by various processes.

In certain embodiments, the syngas is converted to high yields ofalcohols, particularly ethanol. Syngas can be selectively converted toethanol by means of a chemical catalyst, such as described in U.S.patent application Ser. No. 12/166,203, entitled “METHODS AND APPARATUSFOR PRODUCING ALCOHOLS FROM SYNGAS,” filed Jul. 1, 2008, whose assigneeis the same as the assignee of this patent application, and which ishereby incorporated herein by reference. As is known in the art, syngascan also be fermented to a mixture comprising ethanol usingmicroorganisms.

The syngas produced according to the methods and systems of theinvention can also be converted to energy. Syngas-basedenergy-conversion devices include a solid-oxide fuel cell, Stirlingengine, micro-turbine, internal combustion engine, thermoelectricgenerator, scroll expander, gas burner, thermo-photovoltaic device, orgas-to-liquid device. In some cases, the output syngas of two, or more,reactors can be combined to supply syngas to downstream subsystemscomprised of syngas coolers, syngas cleaners, and syngas-basedenergy-conversion devices.

This invention has been described and specific examples of the inventionhave been portrayed. While the invention has been described in terms ofparticular variations, those of ordinary skill in the art will recognizethat the invention is not limited to the variations described. Inaddition, where methods and steps described above indicate certainevents occurring in certain order, those of ordinary skill in the artwill recognize that the ordering of certain steps may be modified andthat such modifications are in accordance with the variations of theinvention. Additionally, certain of the steps may be performedconcurrently in a parallel process when possible, as well as performedsequentially as described above.

All publications, patents, and patent applications cited in thisspecification are herein incorporated by reference in their entirety asif each publication, patent, or patent application were specifically andindividually put forth herein.

In this detailed description, reference has been made to multipleembodiments. Other embodiments that do not provide all of the featuresand advantages set forth herein may be utilized, without departing fromthe spirit and scope of the present invention. To the extent there arevariations of the invention, which are within the spirit of thedisclosure or equivalent to the inventions found in the claims, it isthe intent that this patent will cover those variations as well.

1. A method of forming syngas, the method comprising the steps of: (a)pyrolyzing or torrefying a carbon-containing first feed material to forma pyrolyzed or torrefied first feed material; and (b) converting thepyrolyzed or torrefied first feed material into syngas.
 2. The method ofclaim 1, further comprising converting a second feed material that hasnot been pyrolyzed or torrefied into syngas.
 3. The method of claim 1,further comprising combining the pyrolyzed or torrefied first feedmaterial with a second feed material that has not been pyrolyzed ortorrefied such that both the pyrolyzed or torrefied first feed materialand the second feed material are converted into syngas.
 4. The method ofclaim 1, comprising pyrolyzing a carbon-containing first feed materialto form a pyrolyzed first feed material, torrefying a carbon-containingfeed second material to form a torrefied second feed material, andconverting the pyrolyzed first feed material and the torrefied secondfeed material into syngas.
 5. The method of claim 1, further comprisingintroducing the torrefied first feed material into a pyrolysis reactorto form a pyrolyzed first feed material.
 6. The method of claim 1,wherein converting the pyrolyzed or torrefied first feed material intosyngas comprises passing the pyrolyzed or torrefied first feed materialthrough a heated reaction vessel to form syngas.
 7. The method of claim1, wherein converting the pyrolyzed or torrefied first feed materialinto syngas comprises the substeps of: (i) devolatilizing the pyrolyzedor torrefied first feed material to form a gas phase and/or solid phasein a devolatilization unit; and (ii) passing the gas phase and/or solidphase through a heated reaction vessel to form syngas.
 8. The method ofclaim 1, wherein step (a) is conducted in the presence of a catalyst. 9.A method of forming syngas, the method comprising converting a pyrolyzedor torrefied first feed material and a second carbon-containing feedmaterial that has not been pyrolyzed or torrefied into syngas.
 10. Themethod of claim 9, comprising pyrolyzing a carbon-containing first feedmaterial to form the pyrolyzed first feed material, torrefying acarbon-containing third feed material to form a torrefied third feedmaterial, and converting the pyrolyzed first feed material, the secondfeed material, and the torrefied third feed material into syngas. 11.The method of claim 9, further comprising combining the pyrolyzed ortorrefied first feed material and the second feed material prior toconverting the pyrolyzed or torrefied first feed material and the secondfeed material into syngas.
 12. The method of claim 9, wherein the methodis conducted, at least in part, in the presence of a catalyst.
 13. Themethod of claim 9, wherein converting the pyrolyzed or torrefied firstfeed material and the second feed material into syngas comprises thesteps of: (a) devolatilizing the pyrolyzed or torrefied first feedmaterial and the second feed material to form a gas phase and/or solidphase in a devolatilization unit; and (b) passing the gas phase and/orsolid phase through a heated reaction vessel to form syngas.
 14. Themethod of claim 9, further comprising introducing the torrefied firstfeed material into a pyrolysis reactor to form a pyrolyzed first feedmaterial.
 15. A method of forming syngas, the method comprising thesteps of: (a) devolatilizing a pyrolyzed or torrefied first feedmaterial to form a gas phase and solid phase in a devolatilization unit;and (b) passing the gas phase and solid phase through a heated reactionvessel to form syngas.
 16. The method of claim 15, comprising pyrolyzinga carbon-containing feed material, optionally in the presence of acatalyst, to form the first feed material.
 17. The method of claim 15,comprising torrefying a carbon-containing feed material, optionally inthe presence of a catalyst, to form the first feed material.
 18. Themethod of claim 15, further comprising converting a second feed materialthat has not been pyrolyzed or torrefied into syngas.
 19. The method ofclaim 18, further comprising combining the pyrolyzed or torrefied firstfeed material with a second feed material that has not been pyrolyzed ortorrefied such that both the pyrolyzed or torrefied first feed materialand the second feed material are converted into syngas.
 20. The methodof claim 18, comprising pyrolyzing a carbon-containing first feedmaterial to form the pyrolyzed first feed material, torrefying acarbon-containing third feed material to form a torrefied third feedmaterial, and converting the pyrolyzed first feed material, the secondfeed material, and the torrefied third feed material into syngas. 21.The method of claim 15, further comprising combining the pyrolyzed ortorrefied first feed material and the second feed material prior toconverting the pyrolyzed or torrefied first feed material and the secondfeed material into syngas.
 22. The method of claim 15, furthercomprising introducing the torrefied first feed material into apyrolysis reactor to form a pyrolyzed first feed material.
 23. Themethod of any of claims 1, 9, or 15, wherein the method is conducted, atleast in part, in one or more modular units.
 24. The method of any ofclaims 1, 9, or 15, further comprising the step of converting the syngasto a product.
 25. The method of claim 24, wherein the product isselected from the group consisting of an alcohol, an olefin, analdehyde, a hydrocarbon, an ether, hydrogen, ammonia, and acetic acid.26. The method of claim 25, wherein the hydrocarbon is a linear orbranched C₅-C₁₅ hydrocarbon.
 27. The method of claim 25, wherein thealcohol is methanol.
 28. The method of claim 25, wherein the alcohol isethanol.